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        <h2>
          <span class="refentrytitle">vactrol</span>
        </h2>
        <p>vactrol — 
      Envelope follower unit generator.
          </p>
      </div>
      <div class="refsect1">
        <a id="idp160401040"></a>
        <h2>Description</h2>
        <p>
      Envelope follower unit generator emmulating a Perkin Elmer
      Vactrole VTL5C3/2.
    </p>
      </div>
      <div class="refsect1">
        <a id="idp160402304"></a>
        <h2>Syntax</h2>
        <pre class="synopsis">ares <span class="command"><strong>vactrol</strong></span> asig [iup, idown]</pre>
      </div>
      <div class="refsect1">
        <a id="idp160404448"></a>
        <h2>Initialisation</h2>
        <p>
       <span class="emphasis"><em>iup</em></span> -- The rise time of the filter, which
       defaults to 20,
     </p>
        <p>
       <span class="emphasis"><em>idown</em></span> -- The fall time of the filter, which
       defaults to 3000,
     </p>
      </div>
      <div class="refsect1">
        <a id="idp160406944"></a>
        <h2>Performance</h2>
        <p>
      <span class="emphasis"><em>asig</em></span> -- The signal from which to extract the envelope.
    </p>
      </div>
      <div class="refsect1">
        <a id="idp160408608"></a>
        <h2>Examples</h2>
        <p>
      Here is an example of the vactrol opcode. It uses the file <a class="ulink" href="examples/vactrol.csd" target="_top"><em class="citetitle">vactrol.csd</em></a>.
      </p>
        <div class="example">
          <a id="idp160410464"></a>
          <p class="title">
            <strong>Example 961. Example of the vactrol opcode.</strong>
          </p>
          <div class="example-contents">
            <p>See the sections <a class="link" href="UsingRealTime.html" title="Real-Time Audio"><em class="citetitle">Real-time Audio</em></a> and <a class="link" href="CommandFlags.html" title="Csound command line"><em class="citetitle">Command Line Flags</em></a> for more information on using command line flags.</p>
            <pre class="programlisting">
<span class="csdtag">&lt;CsoundSynthesizer&gt;</span>
<span class="csdtag">&lt;CsInstruments&gt;</span>
        <span class="ohdr">nchnls</span> <span class="op">=</span> 2
        <span class="ohdr">0dbfs</span> <span class="op">=</span> 1
        
    <span class="oblock">instr</span> 1
        a1 <span class="opc">lfo</span> 0.3, 1, 4
        a2 vactrol a1
        a3 <span class="opc">oscili</span> 2, 440
           <span class="opc">out</span>     a1<span class="op">*</span>a3,a2<span class="op">*</span>a3
     <span class="oblock">endin</span>
                    
<span class="csdtag">&lt;/CsInstruments&gt;</span>
<span class="csdtag">&lt;CsScore&gt;</span>
    <span class="stamnt">i</span>1 0 3
    <span class="stamnt">e</span>
<span class="csdtag">&lt;/CsScore&gt;</span>
<span class="csdtag">&lt;/CsoundSynthesizer&gt;</span>
</pre>
          </div>
        </div>
        <p><br class="example-break" />
    </p>
        <p>
      This opcode can reduce zipper noise produced from complex
      envelope tracking as it smooths the transitions.
    </p>
      </div>
      <div class="refsect1">
        <a id="idp160415280"></a>
        <h2>Credits</h2>
        <p>
      </p>
        <table border="0" summary="Simple list" class="simplelist">
          <tr>
            <td>Author: John ffitch</td>
          </tr>
          <tr>
            <td>after Julian Parker</td>
          </tr>
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            <td>New in 6.04</td>
          </tr>
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